Trying to repair my rolling walker which has a thread stripped out in the leg. The thread on wheel is steel and is good so I need to make a new bushing.

The male threads measure 0.459 major dia. and 0.397 minor dia. My metric thread gauge will screw onto the 12mm thread shaft in both the 1.5 and 1.75 holes. Looking at the tool catalogs it would appear that the 1.75 is the more common size. I would like to confirm that before ordering a tap.

My Nardini lathe has a 15 tpi capability which computes to a lead that comes out between the 1.5 and 1.75 metric lead. The plan is to make a new bushing using the 15 tpi setting. Any thoughts?

SDL

08-26-2011, 06:35 PM

Trying to repair my rolling walker which has a thread stripped out in the leg. The thread on wheel is steel and is good so I need to make a new bushing.

The male threads measure 0.459 major dia. and 0.397 minor dia. My metric thread gauge will screw onto the 12mm thread shaft in both the 1.5 and 1.75 holes. Looking at the tool catalogs it would appear that the 1.75 is the more common size. I would like to confirm that before ordering a tap.

My Nardini lathe has a 15 tpi capability which computes to a lead that comes out between the 1.5 and 1.75 metric lead. The plan is to make a new bushing using the 15 tpi setting. Any thoughts?

1.75mm pitch is the standard ISO M12 Coarse pitch, so a good bet.

1.75mm pitch is 14.51tpi so probably close enough or get a tap.

Steve Larner

Tanto

08-26-2011, 07:44 PM

Metric threads are almost always the standard sizes. Unfortunately many suppliers make it look confusing by simply lumping all metric threads in one big list. As Steve says, your fastener is almost certainly a standard M12 which is 1.75 pitch. Whether 15 tpi is close enough will depend on how long the thread is. However is it necessary to replace this with a metric bush? Can you replace both with another fastener that you do have the appropriate tap for?

Juergenwt

08-26-2011, 09:26 PM

tanto you are right on. The beauty of metric threads is that 99% are standard, meaning they are the coarsest thread for a given metric size. You never list the pitch unless for some reason you must use a fine thread. The stupidity of some people listing the pitch regardless, forces one to look up a table to see if there is not another coarser thread available.
Using only standard (coarse) threads allows a shop to greatly reduce the inventory on screws and nuts. ANSI screwed this up real good.

philbur

08-27-2011, 04:42 AM

What's stupid about giving full details about a thread. Assuming that it is a standard pitch because the pitch is not identified can lead to dissapointment.

Phil:)

The stupidity of some people listing the pitch regardless, forces one to look up a table to see if there is not another coarser thread available.

Circlip

08-27-2011, 05:51 AM

I'm having a similar problem in that a piece of threaded rod I have measures 6.35 Dia. but am unsure whether the thread is 0.0385" or 0.05" pitch ?

Regards Ian.

philbur

08-27-2011, 07:13 AM

I don't understand, are you saying you can't tell if it is 20 or 26 threads per inch. Measure an inch and count them!!!

Phil:)

Edit: Do you not have a thread gauge.

I'm having a similar problem in that a piece of threaded rod I have measures 6.35 Dia. but am unsure whether the thread is 0.0385" or 0.05" pitch ?

Regards Ian.

Jaakko Fagerlund

08-27-2011, 08:46 AM

What's stupid about giving full details about a thread. Assuming that it is a standard pitch because the pitch is not identified can lead to dissapointment.

Phil:)
It is stupid as it is standard practice to just tell it is M12. If with metric you tell M12 X 1.75, it means that it ain't a thread from the "most used"/"recommended" list but a fine/special thread.

If it is M12, then it is M12 and not "M12 x 1.75".

Boucher

08-27-2011, 10:44 AM

I donít have a lot of metric resources. A metric nut with a longer engagement would be a better standard than this thin thread gauge. Some of the original confusion results from two of the gauge holes seeming to work as illustrated below.

This shows the thread gauge in the 12X1.5 hole
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0235Small.jpg

This shows the thread gauge in the 12x1.75 hole
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0234Small.jpg

This view of the wheel illustrates why a simple change the bolt thread is not a good option.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0236Small.jpg

In this application there will need to be more than two diameters of thread engagement, which is why, identifying the correct thread becomes increasingly important. The bushing is shown at the lower right.

As stated earlier I have no way of getting a tap over the week end so I will try single pointing a 15 tpi which has a lead between the 1.5 and 1.75

vpt

08-27-2011, 11:00 AM

Strange that 1.75 is considered 'standard'? In automotive imports (honda, toyota, nissan, etc.) the standard metric bolts are almost always on the fine side of the chart. In this situation the 12m would be a 1.25 pitch, that is what I see in cars as being the standard. In fact I don't remember the last time I saw a "coarse" threaded metric bolt.

Scottike

08-27-2011, 11:04 AM

Check it with a metric nut of known pitch, the extra length will let you determine if it's a 1.5 or 1.75 pitch as it will only thread full length at the correct pitch, conversly, a bolt will do the same for the nut that goes into.
I don't know about you, but I'm sure I can find a metric nut or bolt that size residing on/in something in my shop or car. (even if it's "american" made)

philbur

08-27-2011, 11:08 AM

Providing the provider/user is aware of what is standard practice. It they are not then they could get into a whole bunch of trouble. Not everybody is as knowledgeable as yourself. It's interesting to note that all metric thread tables include the pitch size against the standard thread. Why do they do that, do they not realise everybody knows that it is the standard pitch and therefore stating the pitch is stupid.

To include additional information is never stupid. Unnecessary maybe, stupid never. To leave out information that may confuse the uninformed is. Every Yank/Limy/Digger who is not familiar with standard practice regarding metric thread definitions is going to ask -OK it's M12 but what's the pitch? Not many of them bother to read the ISO standard before they go to the hardware store.

Phil:)

It is stupid as it is standard practice to just tell it is M12. If with metric you tell M12 X 1.75, it means that it ain't a thread from the "most used"/"recommended" list but a fine/special thread.

If it is M12, then it is M12 and not "M12 x 1.75".

Lew Hartswick

08-27-2011, 11:45 AM

Providing the provider/user is aware of what is standard practice.
To include additional information is never stupid. Unnecessary maybe, stupid never.
Phil:)
That is one of the nice things about "STANDARDS", there are so many of them.

To include additional information is never stupid. Unnecessary maybe, stupid never.

A big ABSOLUTELY!!!!
...lew...

SDL

08-27-2011, 02:38 PM

Strange that 1.75 is considered 'standard'? In automotive imports (honda, toyota, nissan, etc.) the standard metric bolts are almost always on the fine side of the chart. In this situation the 12m would be a 1.25 pitch, that is what I see in cars as being the standard. In fact I don't remember the last time I saw a "coarse" threaded metric bolt.

Well the coarse series is standard and the Fine pitch should have the pitch specified, that's how it was when I was a cad designer and Engineering manager. In general engineering the only Metric fine I have come across are on pneumatic fittings.

As noted fine pitch quite common on cars but so was BSF when BSW was the std coarse.

Steve Larner

Juergenwt

08-27-2011, 02:55 PM

philbur - read my post again. Nowhere in the rest of the world do people have a problem with M2, M3, M4, M5, M6, M8, M10, M12 etc..Fine threads are usually not kept in stock thereby reducing the inventory. If a company decides to use a fine thread in it's product it will do so for a reason. So if fine threads are used on a bike than the company designed it that way for a reason. You can be sure that the same company will use nothing but standard sizes in it's everyday operations. In day to day usage the standard metric size (coarse) is all that is needed.
It is only in the US where we seem to have a problem because we are so used to listing the pitch for inch threads.
I like the reply from Jaakko Fagerlund.

kc5ezc

08-27-2011, 03:01 PM

No worry about metric coarse or fine bolts or nuts here. ALL the stores only have one (1) pitch in stock. Usually coarse. Of course they will order some fine pitch and get them 'real soon now.' that means 72 hours to a week, maybe.
Even the auto parts places seem to have only one pitch.
Auto dealers may have the part, but under a manufacturers number. They do not know the pitch.
It is only a 1 hour drive (one way)to a good nut and bolt place. Of course they are not open after 5 pm and on weekends.
Rant off.

Forrest Addy

08-27-2011, 03:02 PM

There are NO preferred imperial thread pitches close enough to metric to properly engage a metric nut unless you thread undersized. Some are close but 1.75 mm pitch works out to 14.51 threads per inch. Half in the middle. The result is loose, unsatisfactory, easily sheared, will work loose with a couple of shocks, and bogus.

Some battles are not worth fighting to a successful conclusion. Buy a cheap M12 tap and be done with it.

Boucher

08-27-2011, 03:09 PM

The bushing threaded to 15 tpi will screw onto the male metric thread. It snuggs up at 8 turns and gets tight at 9. It would have been nice to have a couple of metric nuts. I have imperial threads up to 3" but very few metric.

Juergenwt

08-27-2011, 03:22 PM

Boucher - Get a standard M12 nut and try it and than order a standard M12 tap.
Don't mix the two (inch and metric) systems. Those gages you show are made for the sales girls at Home Depot or Menards. For a professional they are useless. Whoever made those did not have a clue what he was doing. Those stores should not stock metric fine and the properly don't. If they do, they will not sell any for years to come. Remember what I said: reduce inventory!

Juergenwt

08-27-2011, 03:26 PM

Boucher - go to the next Hardware store and buy a M12 nut.

Carld

08-27-2011, 03:44 PM

All the hardware stores I have been to have both fine and coarse thread metric and imperial bolts and nuts.

I have never been to any store selling bolts and nuts that only have coarse or fine thread.

I also have found few hardware store workers that knew much about bolts and sizes and grades. And, at 70 years of age I have been in a hell of a lot of hardware stores in several states.

I have never heard of one thread pitch being "The Standard" size. On the other hand I am not an engineer nor do I do CAD so the "Standard" may only occur in those areas, not in everyday usage.

Juergenwt

08-27-2011, 04:02 PM

Carld - it's a learning process. A little story about GM. When GM decided to go all metric (system preferred by US government) they tried to keep track of the cost for converting so they would be able for a reimbursement from the government. By the third year they stopped doing that because the saving far outweigh the expense. In the beginning they talked about zillions of dollars in cost. In the end they ended up with zillions in saving. One of the main reasons was the reduction in inventory from screws to cutting tools to print sizes etc..

SDL

08-27-2011, 04:18 PM

All the hardware stores I have been to have both fine and coarse thread metric and imperial bolts and nuts.

I have never been to any store selling bolts and nuts that only have coarse or fine thread.

I also have found few hardware store workers that knew much about bolts and sizes and grades. And, at 70 years of age I have been in a hell of a lot of hardware stores in several states.

I have never heard of one thread pitch being "The Standard" size. On the other hand I am not an engineer nor do I do CAD so the "Standard" may only occur in those areas, not in everyday usage.

The Std is ISO 262 for those not allergic to Tiff links see here halfway down preferred sizes ( By the way welcome back tiff)

sets out quite well how USA ANSI always specifies pitch and the rest of the world (who understand and follow the standards) Don,t specify pitch if coarse.

Steve Larner

John Garner

08-27-2011, 04:37 PM

Boucher --

If you haven't already ruled out an epoxy fix -- grease the male thread, degrease the female thread, coat both sides with mixed epoxy, assemble, and wait for the epoxy to cure -- with JB Weld, Marine-Tex, or any of a couple dozed similar products, consider it.

John

philbur

08-27-2011, 05:50 PM

ISO 262 contains no reference to using only the diameter when making reference to course threads. As far as I can determine nor do the other 4 ISO standards relating to metric threads.

Your wikipedia reference says "can omit". Not "must" or "shall omit".

Phil:)

The Std is ISO 262 for those not allergic to Tiff links see here halfway down preferred sizes ( By the way welcome back tiff)

sets out quite well how USA ANSI always specifies pitch and the rest of the world (who understand and follow the standards) Don,t specify pitch if coarse.

Steve Larner

Carld

08-27-2011, 06:44 PM

Ok, so for drawing purposes if your using a coarse thread metric bolt all you have to print is M10 but if you want to spec. a fine thread you must print out M10-1.25mm.

That's interesting but I wonder how many mistakes are made because of drafting errors? I would prefer to know the exact pitch of the thread rather depend on someone putting M10 on the print. I would be making a phone call at that point.

SDL

08-27-2011, 07:00 PM

Ok, so for drawing purposes if your using a coarse thread metric bolt all you have to print is M10 but if you want to spec. a fine thread you must print out M10-1.25mm.

That's interesting but I wonder how many mistakes are made because of drafting errors? I would prefer to know the exact pitch of the thread rather depend on someone putting M10 on the print. I would be making a phone call at that point.

That,s exactly how its been done at the 5 places I have worked at in the last 30 years in the UK and sounds like how its done in Finland but not Norway.

Most of the problems I have had have been where the pitch for a fine series has been on the drawing but ignored, as it is just so rare in the industries I have worked in, I'm sure the fine series are common in Automotive and Aerospace etc.

Most UK graduates now days don't even understand the tolerancing of limits and fits on threads.

Steve Larner

Tanto

08-27-2011, 07:49 PM

Steve is quite right. It is convention to call only M10 etc when drafting. That does specify the pitch, since none is called it is therefore metric coarse. If the pitch is called, that act in itself implies something other than metric coarse. Of course it's possible to specify the pitch throughout if you want, however it would be like saying the time is 12 "of the clock", nobody gets confused when somebody says it's 12 o'clock, despite that also being an abbreviation used by convention. Do you also walk into a computer store and order your random access memory to upgrade your machine? Personally I order RAM, and I haven't instead been handed a hamburger or anything else instead of what I was expecting. No confusion required, it's all just convention.

philbur

08-27-2011, 08:24 PM

Your analogies leave a lot to be desired. 12 o'clock is an abbreviation of 12 of the clock with all the necessary elements still there. RAM is an abbreviation of random access memory which you would not understand if you were not computer savvy. M10 is a truncated version of M10 x 1.5 which you could not guess at unless you were aware of the convention, which is quite possible in a home shop environment. The reference to the Hamburger is just stupid and kinda destroys you point right at the the end.

Communicating information by virtue of it's absence will always be a risky business, especially when you are unaware of the knowledge of the person you are communicating with.

This discussion started with somebody saying to use M10 x 1.5 was stupid. Well it isn't the accepted convention but it is far from stupid.

Phil:)

Edit: Is it stupid or wrong to use the phrase random access memory instead of RAM.

Steve is quite right. It is convention to call only M10 etc when drafting. That does specify the pitch, since none is called it is therefore metric coarse. If the pitch is called, that act in itself implies something other than metric coarse. Of course it's possible to specify the pitch throughout if you want, however it would be like saying the time is 12 "of the clock", nobody gets confused when somebody says it's 12 o'clock, despite that also being an abbreviation used by convention. Do you also walk into a computer store and order your random access memory to upgrade your machine? Personally I order RAM, and I haven't instead been handed a hamburger or anything else instead of what I was expecting. No confusion required, it's all just convention.

Tanto

08-27-2011, 10:04 PM

Take a chill Pill Phil, it was not me who said it was "stupid", I am simply saying what is the convention used in industry. If you have an opinion otherwise then you are perfectly entitled to that, however this is the conventional used as an abbreviation for metric coarse.

M10 is a truncated version of M10 x 1.5 which you could not guess at unless you were aware of the convention, which is quite possible in a home shop environment.

If you are not aware of the convention, then hopefully now you are. It seems plenty of other people here who routinely work with metric fasteners are.

Truncation and abbreviation are synonyms in this sense Phil, M12 is an abbreviation of M12 x 1.75. Communication of any description is risky Phil, indeed this very post drives that home. When I initially wrote M12 x 1.75 I mis-typed .75, had I simply written M12 the mistake wouldn't have occurred. Of course any experienced person in this field would question why it was not written 0.75, that also being convention!

As for hamburgers, I shall certainly make a mental note to myself that you have no sense of humour.